This section provides background information to facilitate a better understanding of the various aspects of the disclosure. It should be understood that the statements in this section of this document are to be read in this light, and not as admissions of prior art.
Agricultural harvesting machines such as combine harvesters are used to reap, thresh, and winnow grain crops such as wheat, rye, barley, corn, soybeans, oats, flax, sunflower, and canola. More specifically, combine harvesters are used to cut grain crops at the base, separate the grains from the remainder of the plant (the chaff), and sort the grain from the chaff. These machines require special adaptations to accommodate specific crops, navigate through field landscapes, and resist damage from the crops, stone, and the elements; especially moisture and high temperature which can lead to the degradation of the machine's rubber components.
Generally harvesting machines gather crops using a header having crop dividers which define crop gathering gaps as the machine moves through a field. The gathered crops are pushed by a reel into a cutter bar, which runs the length of the header and is equipped with teeth made of metal or plastic to cut crops at their base. Headers may have a rigid or flexible header platform depending upon the operational needs and the crop being harvested. Flexible header platforms or “flex headers” have a cutter bar which is capable of flexing over uneven terrain. Machines using flex headers are most often used to cut soybeans, whereas conventional header platforms have a rigid cutter bar and are most often used to cut cereal crops. Freshly cut crops fall behind the cutter bar and onto a plurality of side by side draper belts which are wrapped around parallel spaced rollers. Draper belts function primarily to consolidate crops and move the crops from the header towards the threshing drum. Crops are fed into the threshing drum by spinning augurs. Inside the threshing drum, the grains are shaken from the plant. Grains fall through sieves into a grain collecting tank, and the plant waste, or chaff, is moved to the back of the machine by conveyor belts for later disposal.
Draper belts are an important component of agricultural harvesters. These belts are often subject to prolonged sun exposure, high temperatures, cold temperatures, rain, moisture, dirt, plant debris, and stone, as well as high levels of friction from the moving machinery and crops. Furthermore, water is known to migrate through the rubber belts carrying corrosive elements and salts which can degrade the belt. Draper belts are typically called upon to operate for long periods of time and over a service life of many years. For these reasons it is necessary that draper belts be specially adapted to maximize durability and service life, and it is desirable for such adaptations to be cost effective.
Some improvements in reducing the susceptibility of draper belts to damage have been made and are reported in the prior art. For instance, U.S. Pat. No. 7,543,428 discloses a seamless draper belt formed from an elongated flat base structure of fabric and rubber. This patent teaches that the belt side edges can be folded over on themselves before curing, or in the alternative separate uncured rubber strips may be placed along the side edges to form a re-enforcing hem to reduce belt edge damage. However, bending of the belt inherently creates a weak point at the center of the fold in the belt edges. Furthermore, separate rubber strips can be vulnerable to being dislodged from the belt edges by damaging events as a result of the rubber composition and belt design, leaving the belt edges and reinforcing fabric within the belt at a greater risk for even more catastrophic belt damage.
Other prior art draper belts have made efforts to reduce their susceptibility to damage, but these belts are inadequate. In an attempt to reduce edge damage, United States Patent Application Publication No. 2007/0238565 A1 shows a draper belt provided with reinforcing plies extending spanwise inwardly from each belt edge. Cleats, oriented spanwise to the belt, are each provided with cleat bases of extended dimension to extend the region of the belt and the cleat which are subjected to stress and strain as the cleat and belt turn over a mounting roller. These reinforcing plies extending from each edge of the belt do not alter the belt edges in a way that could make them any more or less susceptible to damage than the belt as a whole. Furthermore, the belt edges of this draper belt are not strong enough to resist damage from buckling if the belt mis-tracks.
It is common for draper belts of the prior art to fail for one or more reasons. Frequently draper belts mis-track and are damaged by either the front or the back end of the machine header as a result of less than optimal belt edge design and inadequate construction. Accordingly there is a need for a specially adapted draper belt having significantly more durable edges than draper belts of the prior art.